After World War I, in response to the depressed economic circumstances of the 1920s, Rolls Royce introduced a cheaper model in 1922, the 20hp, equipped with a 3128cc in-line 6-cylinder engine, with an output of 50 horsepower at 3000 rpm. Quite short of power, the car nevertheless had a good sales success, and was replaced in 1929 by the 20/25, which had an engine increased to 3669cc.